Novel Thermoplastic Fibre-Metal Laminates Manufactured by Vacuum Resin Infusion: The Effect of Surface Treatments on Interfacial Bonding

The manufacturing process of a new generation of thermoplastic fibre-metal laminates (TP-FMLs) was investigated. A vacuum assisted resin infusion method was used to produce the hybrid laminates. The effect of various chemical and physical treatments on the surface morphology of the aluminium (Al) alloy sheets and on the bond strength at the metal-composite interface was examined. The wettability, topography and chemical composition of the treated Al alloy sheets were studied by employing contact-angle goniometry, coherence scanning interferometry, profilometry and X-ray photoelectron spectroscopy. The results showed that the applied treatments on the Al alloy sheet changed the surface morphology and surface energy in a different degree, which in turn effectively enhanced the interfacial bond strength between the constituents. In addition, the flexural, interlaminar shear strength and interlaminar fracture toughness of the manufactured TP-FMLs with the optimum metal surface treatment were evaluated. The experimental results of the TP-FMLs were compared to an equivalent thermoplastic composite. The composite-metal interface and the fracture surface characteristics were examined under scanning electron microscopy. In-situ polymerisation was found to play a key role in bonding the treated Al alloy with the composite layer during manufacturing

Designing the Electrode Geometry and Electrolyte to Enhance the Product Selectivity and Activity in Carbon Dioxide Electroreduction

Excessive utilization of the fossil fuels due to the rapid growth of the global population has resulted in a dramatic increase in the carbon dioxide (CO2) level in the atmosphere which is the main reason for global warming and climate change. Therefore, green technologies are in high demand to develop carbon-neutral energy cycles. In this regard, CO2 electroreduction (CO2ER) has been proposed as a promising approach for CO2 utilization. CO2ER can mitigate the CO2 level in the atmosphere as well as produce value-added chemicals and fuels at ambient conditions. Despite the benefits of CO2 electroreduction, the low energy efficiency and poor product selectivity in CO2ER have retarded large-scale application of this process. Numerous strategies have been proposed to control the selectivity and enhance the catalytic activity in CO2ER. However, the electrode geometry and electrolyte composition in the aqueous electrolytes have been less studied in CO2ER compared to other factors such as catalyst materials and catalyst morphology. In the first part of this work, the effect of electrode geometry on CO2ER was examined for both polycrystalline Cu and Ag metals. For this purpose, CO2ER was performed on three different electrode shapes, flag (2-D), foil coil (3-D), and wire coil (3-D), in 0.1 M potassium bicarbonate (KHCO3). In addition to the experimental study, COMSOL Multiphysics was also used to predict the current, potential, and electric field distribution. Results showed that both foil coil and wire coil have a higher CO2ER catalytic activity in relation to the flag electrodesregardless of the electrode material (Cu or Ag). By changing the electrode geometry from flag to foil coil and wire coil, a 69% and 76% increase, respectively, in faradaic efficiency (FE) for C2 products were observed. However, the FE for methane increased only on Cu foil coil (104% increase compared to Cu flag), and the Cu wire coil showed a lower FEmethanecompared to other electrode shapes. The shape of the electrode also affected the CO selectivity and activity on Ag electrodes. Ag foil coil and Ag wire coil had a 20% and 5% increase in FE for CO compared to Ag flag at -1.12 V. The observed superior performance on foil coil and wire coil electrodes can be explained by the high electric fields around them due to the larger amount ofsharp and high curvature points on the surface compared to the flag electrode. Enhanced electric field at the interface causes more cations to adsorb to the surface and stabilize the intermediates such as CO2 •− radicals which are needed for CO2ER. In the second part of this study, the effect of anion and cation in ionic additives on the product selectivity and activity of the Cu catalyst in CO2ER was investigated. For the anion study, 10 mM of an ionic liquid (IL) with the same cation 1-butyl-3-methylimidazolium [BMIM]+ and various anions: bis(trifluoromethylsulfonyl)imide [NTF2]–, triflate [OTF]–, acetate [Ac]–, chloride [Cl]–, and dicyanamide[DCA]– was used. The results showed that although imidazolium-based ILs have a potential to enhance CO2ER due to the interaction of CO2 with imidazolium ring, the anion of IL also plays an important role in CO2ER. It was found that there is a relationship between the hydrophobicity of the anion and CO2ER activity. Higher CO2ER activity was found for more hydrophobic ILs such as [BMIM][NTF2]. In all ILs except for [BMIM][DCA], the formate FE% increased by adding the ILs to the electrolyte. The maximum increase in formate (38.7% FE) was observed for [BMIM][NTF2] at -0.92 V which has the highest hydrophobicity compared to other ILs. However, [BMIM][DCA] which has a high hydrophilicity and a low CO2 affinity shut off the CO2ER and enhanced HER at all potentials. This observation is attributed to the surface poisoning due to the strong adsorption of [BMIM][DCA] which was confirmed by X-ray photoelectron spectroscopy (XPS). Changing the cation from [BMIM]+ to sodium (Na+) and potassium (K+) with [NTF2]– and [DCA]– anions showed that the cation of the additive also plays a role in CO2ER especially for [NTF2]–-based additives. Results showed that all [NTF2]–-based additives increased the FE for formate compared to the additive-free electrolyte (9% FE). Among [NTF2]–-baased additives, [BMIM][NTF2] had a higher FE for formate (38.7%) compared to K[NTF2] (23.2%) and Na[NTF2] (18.5%) at -0.92 V probably due to the presence of imidazolium cation which can further stabilize the intermediates on the surface and enhance CO2ER. However, the FE for C2products (ethylene and ethanol) at high negative potentials were lower for [BMIM][NTF2] and K[NTF2] compared to the additive-free and Na[NTF2] electrolytes. This observation can be due to the presence of [BMIM]+ and hydrated K+ cations on the surface and inhibiting the *CO dimerization which is needed for the formation of C2 products. Electrolytes containing [DCA]–-based additives had a very high HER activity and low CO2ER activity regardless of the cation nature. This is due to the strong adsorption of [DCA]– anions on the surface which poisons the surface for CO2ER

Influence of Electric Field and Current Distribution due to Electrode Geometry on CO₂ Electroreduction

The electrode geometry significantly influences the selectivity and activity in CO2 electroreduction (CO2ER) even when the same materials are utilized. In order to obtain insight into why the electrode geometry impacts the CO2ER, a computational study using COMSOL Multiphysics software was conducted. A three-dimensional (3-D) simulation was performed to compare three electrodes with the same surface area (0.9 cm2) and different geometries: a two-dimensional (2-D) flag, a 3-D foil coil, and a 3-D wire coil, all composed of silver. The results showed that the edges and corners have a higher current density and stronger electric field compared with the flat regions. Therefore, the foil coil and wire coil, which have more edges and corners compared to the flag, had a higher total current, a stronger electric field, and a more uniform current distribution on the surface. The high current at the edges and corners can decrease the energy barrier needed for CO2ER. An enhanced electric field can also increase the concentration of cations at the interface, leading to stabilization of the intermediates such as CO2•– radicals and improvement in CO2ER. The interfacial properties in the electrode–electrolyte interface are also impacted by the electrode geometry. It was also observed that the edges and corners have a higher local pH and a lower CO2 concentration due to the enhanced CO2ER reactions at these sharp points. The calculations in this study can further explain the enhanced performance of foil coil and wire coil electrodes, which had been observed in our previous report. This work illustrates how important it is to include electric field and current distribution considerations in the design of electrochemical reactors

Novel epoxy/metal phthalocyanines nanocomposite coatings for corrosion protection of carbon steel

In this study, epoxy/metal phthalocyanines nanocomposites (NiPc/Epoxy, CuPc/Epoxy, and ZnPc/Epoxy) are employed to protect carbon steel corrosion in 3.5% NaCl solution. The corrosion performances of the nanocomposites coatings were evaluated by using electrochemical impedance spectroscopy (EIS), open circuit potential (OCP) and scanning electron microscopy (SEM) measurements. The mechanical property of the coating system was investigated using nanoindentation technique. The results indicated that the incorporation of metal phthalocyanines pigments into epoxy resin coating significantly enhances the corrosion resistance as well as the hardness of epoxy coatings.Metal phthalocyanines pigments are able to cure the defect in epoxy resin and prevent the diffusion of corrosive electrolyte to carbon steel substrate. It was found that NiPc/Epoxy nanocomposite gave the best protection performance than others

A new corrosion protection approach for aeronautical applications combining a Phenol-paraPhenyleneDiAmine benzoxazine resin applied on sulfo-tartaric anodized aluminum

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